Batter in feast containing half of lemon? (6)
I believe the answer is:
eyelid
'batter' is the definition.
(as in batting your eyelids)
'in feast containing half of lemon?' is the wordplay.
'in feast' becomes 'eid' (feast in Islam. I am not sure about the 'in' bit.).
'containing' indicates putting letters inside.
'half of' means to take half the letters.
'lemon?' becomes 'yellow' (lemon is a kind of yellow).
'yellow' halved is 'yel'.
'eid' placed around 'yel' is 'EYELID'.
(Other definitions for eyelid that I've seen before include "Skin for blinking" , "Batting membrane?" , "Cover for organ of sight" , "Natural optic occluder" , "Natural optic cover" .)